CHEMSITRY
UNIT: STOICHIOMETRY
Name: ______Date: ______MOD: ______
Percent Yield of a Salt: Student Data Sheet
DATA TABLE
1. Mass of evaporating dish, cover, and NaHCO3 ______g
2. Mass of evaporating dish and cover (first heating) ______g
3. Mass of evaporating dish and cover (second heating) ______g
4. Constant mass of evaporating dish and cover ______g
5. Mass of NaHCO3 ______g
6. Mass of evaporating dish, cover, and residue (first heating) ______g
7. Mass of evaporating dish, cover, and residue (second heating) ______g
8. Constant mass of evaporating dish, cover, and residue ______g
9. Mass of residue (experimental yield) ______g
ANALYSIS
1. Write a balanced equation for this reaction if the reactants yield a salt, a gas, and water as products.
______(s) + HCl(aq) g NaCl(s) + CO2(g) + ______(l)
2. Calculate the number of moles of NaHCO3 used in the experiment.
#5 g NaHCO3 x 1 mole = moles NaHCO3
molar mass of NaHCO3
3. Use the balanced equation and the moles of NaHCO3 computed in #2 to calculate the moles of solid product and the mass of solid product that should be produced (theoretical yield).
Theoretical Yield: mol NaHCO3 x mol NaCl x g NaCl = g NaCl
mol NaHCO3 mol NaCl
4. Calculate the % yield of salt.
% yield = Data Entry #9 g x 100 = %
Answer to Question #3 g
5. Perform an error analysis.
a) Calculate the % error using the theoretical yield from analysis question #3 and your experimental yield from the data table.
% error = ½theoretical yield – experimental yield ½ x 100
theoretical yield
Theoretical = Answer to question #3
Experimental = Data Entry #9
6. In an attempt to save time, one of the students in your group suggested that you eliminate steps 1 and 6 (the repeated heating, cooling, and mass measurement steps).
What effect might this have on:
a) the experimental yield?
b) the theoretical yield?
c) the % yield?
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